With over five years of experience in tribology and materials science, I am a PhD researcher at Vienna University of Technology, where I explore new applications for recycled plastics that reduce friction and wear. I am passionate about finding innovative solutions that enhance the performance and value of recycled plastics, without requiring extensive changes in the recycling industry. In addition to my PhD research, I am also an ambassador for Resources, Conservation & Recycling, a leading journal in the field of waste management and environmental engineering. I write impact summaries for articles being published every month and advise on worldwide and region-specific outreach strategies.
Unleashing the Hidden Potential of Recycled Plastics in Tribology – Part 1: Polyethylene
What happens to recycled plastic?
Plastic recycling is great. It is everywhere. Or at least, the talk of it is everywhere. In places with good waste management infrastructure, separately discarded plastic waste goes through a system of sorting, shredding and washing, and it is then put into an extruder to melt it and turn it into granules. These granules can be used to make new products. However, less than 9% of newly produced products use recycled plastic. One big reason for this low number is that recycled plastics often do not make the cut when it comes to meeting the mechanical requirements of various applications. On top of this, there are other concerns such as food safety requirements which limit the use of recycled granules to produce food packaging, and as a consequence, they end up in low-value products. To overcome this, there is a need to look elsewhere for new high-value applications for recycled plastics.
Tribology to the rescue!
What if, instead of fixating on the individual properties of recycled plastics, we started looking at these materials from a system perspective? Our research reveals that recycled high-density polyethylene (HDPE; ♻️ 2) is a game-changer within the realm of tribology, the science of friction and wear. Despite some variations in melt flow and mechanical properties induced by reprocessing (extrusion), recycled HDPE has great tribological properties. The coefficient of friction and wear rate when rubbed against steel remained surprisingly low, putting it in the same league as star performers such as ultra-high-molecular-weight polyethylene (UHMWPE). In short, recycled HDPE can shine when it’s considered as part of a system, rather than just a standalone component.
Why does this matter?
For starters, their use in tribology offers a way out for recycled plastics and ensures their usage in high-value applications. Recycled HDPE offers a more eco-friendly and cost-effective alternative to other, expensive and less sustainable polymers such as POM, PBT and PTFE. Using recycled HDPE, even in small amounts, can have a more significant environmental impact than larger substitutions of other polymers with only slightly smaller environmental footprints in tribological applications.
Recycling with a purpose
This breakthrough is more than just a one-off discovery; it’s part of a growing movement towards sustainable, smart recycling. We believe our concept has the potential to unlock a world of high-value applications and pave the way for a greener future. So, if you’re passionate about tribology and making a positive impact on our world, keep an eye on this exciting development. Recycled plastics in tribology might just be the game-changer we’ve been waiting for.
Read the article on Resources, Conservation and Recycling (open access):
Raghuram, H., Roitner, J., Jones, M. P., & Archodoulaki, V. M. (2023). Recycling of polyethylene: Tribology assessment. Resources, Conservation and Recycling, 192, 106925. https://doi.org/10.1016/j.resconrec.2023.106925